26 



BITTER PIT INVESTIGATION. 



Table IV— Specimens oe Normal and Diseased Pears and Apples Examined for the 



Presence op Arsenic. 



Skin only, Josephine Pears (Bitter Pit) . . . . Negative 



Diseased portion ,, „ . . . . „ 



Skin only ,, (Normal) .. .. „ 



Pulp only 



Skin of Apple, Esopus Spitzenberg (Bitter Pit) . . „ 



Pulp of Apple „ „ . . „ 



Since it was known that unsprayed apples were affected with Bitter Pit, a committee was 

 appointed, including Professor Ewart, to collect samples. The following varieties were obtained 

 from orchards within a convenient distance of Melbourne, viz., Stunner Pippin, Dumelow's 

 Seedling, Northern Spy, and Rymer. They were carefully examined by the Biologist of the 

 Agricultural Department, and acknowledged by the committee to be genuine cases of Bitter Pit. 



The samples were examined for mineral poison, and the following report was forwarded by 

 Mr. Scott : — Result of examination of unsprayed apples affected with Bitter Pit, for the detection 

 of mineral poisons — " The samples were examined by the undermentioned methods : — The 

 apples were first sliced and dried in a water bath, at 100° C. The dried material was then 

 ground into powder and thoroughly mixed. A portion was then charred on a sand bath, at a 

 low temperature, for about fifteen minutes, by means of strong sulphuric acid ; then extracted 

 with hot water, and tested for arsenic in Marsh's apparatus, afterwards treated with hydrochloric 

 acid, and likewise tested in Marsh's apparatus. 



" Another portion of the dried material was incinerated at a low heat, and the ash dissolved 

 in hydrochloric acid, and a current of sulphuretted hydrogen was passed through the solution. I 

 did not obtain any mirror by means of Marsh's test or coloration of liquid precipitate by the 

 sulphuretted hydrogen. 



" The examination, therefore, revealed no evidence of the presence of mineral poisons in 

 the fruit." 



The presence of Bitter Pit in unsprayed apples has now been conclusively proved, and it 

 has been produced in trees where no spray of any kind was used. Chemical analysis also failed 

 to reveal the presence of mineral poisons, so that the theory that spraying with poisonous 

 compounds is the cause of Bitter Pit is no longer tenable. 



Since writing the above, I have received a copy of the " Proceedings of the Royal 

 Society of Victoria," issued March, 1912, in which Professor Ewart (32) contributes a paper 

 " On Bitter Pit and the Sensitivity of Apples to Poisons." As he shows in this paper " that it is 

 not necessary to withdraw or modify any part of Dr. White's paper, except in so far as her tentative 

 theory, that the source of poisoning might be from poisonous sprays, only holds good partly, for 

 Bitter Pit may also occur in orchards which have never been sprayed with poisonous compounds," 

 there is no necessity to repeat the account of the rebutting experiments carried out as suggested 

 by Dr. White herself. The occurrence of Bitter Pit in unsprayed orchards has now been 

 acknowledged, and the only explanation given is that "the poison must be absorbed from the 

 soil." He further acknowledges that to find out what poisons are absorbed from the soil or subsoil 

 is " a chemical problem of some difficulty," so that the chemist will require to make a special 

 examination of the soils of our orchards for this purpose. Professor Ewart has carried out a vast 

 amount of research work in connexion with " The Sensitivity of Apples to Poisons," both in 

 uninjured fruit and " prepared " fruit, i.e., when fragments of the cuticle were removed without 

 injuring the cells beneath the epidermis. (Part I.) The action of poisons including poisonous 

 sprays on the tree itself, as well as on the fruit, is a subject well worthy of investigation, especially 

 under Australian conditions, and the professor deserves great credit for having initiated it. But 



